Compressor Unloader Valve Location On DD15

I know the location of unloader valve but honestly I don't want make you upset this Christmas day.

 

the valve is under cup. two small screws must be taken off to get to unloader valve. on DD15 once I tried to replace it and did not succeed. the air compressor must be taken off or the high pressure fuel pump. 5-6 hours job atleast.

 

It on top of the air compressor. Air compressor is located on the driver side right on the flywheel. You can change it without taking the air compressor out but it is going to a pain in the rear. Use small Allen keys to remove the two screw for the unloader. When installing the new one use a long screwdriver to push down the unloader valve and hold it, start one of the screws with a hand slowly. Good luck

 

Why do you think it is the unloader valve? Was the system purging like it is now prior. replacing the dryer cartridge? Something to consider, just because you replaced the dryer cartridge, does not fix the purge valve or heater element.

While the cartridge is important, the rest of the dryer can be malfunctioning.
Also have you considered the governor?

Working on the air compressor on a DD15 can be difficult, it is mounted at the rear of the engine on the drivers side, off of the accesory drive. It has the power steering pump mounted to the end of the compressor.

When getting into the compressor and other items running off the acessory drive, you really need to put things back together with new O-rings, seals, gaskets bolts and crush washers.
You will end up with major oil leaks if things are not replaced properly.

 

have you changed it on DD15 without removing the compressor?

 

http://www.thetruckersreport.com/tr...ssor-on-cascadia-running-continuously.146084/

 

The unloaded valve can be replaced with the air compressor installed. I have replaced them many times in the cascadias. It's a lot easier if you remove the left fender. If this doesn't fix the compressor running all the time, it is most likely the governor line running from the compressor to the governor. The line gets a hole in it causing it to leak. You will watch the air gauge build and you can watch it drain back down to governor cut in and then build again. It's a never ending cycle. Hard to diagnose cause usually you can't hear the air leak cause the engine has to be running.